In particular in receiving and transmitting technology it is frequently conventional on a receiving and/or transmitting path to not only relay the radio-frequency signals to be transmitted or to be received (called RF signals in brief below), but to also supply, via this path, the active components integrated into the connected antennae, amplifiers, pre-amplifiers etc., with direct voltage for the current supply and/or to also at least transmit via the path the audio-frequency (AF) alternating voltages (for example pilot signals) to control and regulate the components.
Additional apparatuses provided on the receiving or transmitting paths such as in particular radio-frequency filters are however, frequently not in a position here to also accept and transmit the direct voltage and/or audio-frequency alternating voltage also required for the current supply in addition to the radio-frequency signals, for example for the pilot signals mentioned, as the problem is that direct voltage and/or AF outputs of this type have to be designed such that they as far as possible do not change the properties of the filter. In turn, this only functions when the circumventions to the RF lines are decoupled (which frequently takes place using a coil or a λ/4 line) and consequently only extremely highly damped radio-frequency signals can be transmitted on the output path. A conventional technique is therefore to provide a circumvention in the form of an output or bypass path by means of which a direct voltage also transmitted on the radio-frequency path or an audio-frequency alternating voltage can be output and input again into the radio-frequency path at another point. As a result, for example, a radio-frequency path provided with a radio-frequency filter or a duplexer can be circumvented or bridged.
For this purpose, solutions were hitherto known, in which for example, a coil or a λ/4 line or one or more conductor plates with multi-stage low-pass filters were used, which were generally discretely constructed.
For space reasons, it has also already been proposed to use a λ/4 line together with so-called bushing capacitors, in which a dielectric circumventing the line was provided on the bypass path in the input or in the output region of the λ/4 line, which dielectric was surrounded by a cylindrical sleeve producing the capacitor, which sleeve had to be soldered in a corresponding recess, for example in a housing wall of a radio-frequency filter or duplexer. Various drawbacks were connected with this technology, however.
An input and output circuit for direct voltage and/or audio-frequency signals for RF paths is, for example, also known from U.S. Pat. No. 5,296,825 A. This input/output circuit has an output path via a resistor and a capacitor connected in series thereto. The output path also comprises a transformation line, the electrical length of which is λ/4±Δ wherein a λ corresponds to a wavelength on the RF path. The capacitor device mentioned makes possible a short for a certain frequency.
The decoupling cannot, however, be described as adequate in each case.
The object of the exemplary illustrative non-limiting technology herein is therefore to provide an improved direct voltage and/or audio-frequency circumvention and/or output for a radio-frequency path, in particular for radio-frequency filters, duplexers or other electrical/electronic apparatuses, which is constructed simply and is highly effective from the electrical point of view.
Apart from a further cost saving, the advantage according to an exemplary illustrative non-limiting implementation is inter alia that the corresponding direct voltage and/or audio-frequency voltage output and/or circumvention can be much more easily assembled or also disassembled in the case of repair work. In addition, simple standard parts may be used which make special manufacturing superfluous. Finally, the outlay for space is much less compared to conventional solutions as, for example, no so-called temperature traps, which were previously otherwise necessary, have to be integrated in the housing.